1. Field of the Invention
The present invention relates to a process for the preparation of isocyanuric acid triesters.
It is a primary object of the present invention to provide a process according to which isocyanuric acid triesters, which are useful in various industries such as the chemical industry, the resin industry and the paint industry, can easily be prepared with economic advantages. The process of the present invention can be used to prepare various known useful isocyanuric acid triesters.
The isocyanuric acid triesters that can be prepared according to the process of the present invention include all isocyanuric acid triesters except triaryl isocyanurates. The process of the present invention is especially preferred for the preparation of trialkyl isocyanurates and triaralkyl isocyanurates.
2. Description of the Prior Art
Isocyanuric acid triesters have previously been used as starting materials for preparing heat-resistant resins, modifiers, additives and the like, but the specific esters that are actually used on an industrial scale are limited in number and they are quite expensive. Accordingly, these esters are not manufactured in large quantities.
As conventional methods for the preparation of these isocyanuric acid triesters, there can be mentioned, for example, (1) a method in which a corresponding organic isocyanic acid ester is trimerized, (2) a method in which a corresponding organic halogen compound is subjected to substitution reaction with an alkali cyanate and then the resulting isocyanic acid ester is trimerized and (3) a method in which a corresponding organic halogen compound is subjected to substitution reaction with cyanuric chloride. According to the method (1), isocyanuric acid triesters can be prepared most easily, but this method (1) is disadvantageous because the isocyanic acid esters that are now industrially available are very expensive and few in number. In each of the methods (2) and (3), an organic halogen compound is used as the starting material. Since the reactivity of the organic halogen compound to the intended substitution reaction is very low, the isocyanuric acid triesters that can be prepared according to these methods (2) and (3) are limited to a few triesters, for example, triallyl isocyanurate.